This study is designed to recruit and prospectively follow a cohort of women and their husbands to assess the effects of exposure to organophosphate (OP) pesticides on adverse reproductive outcomes in both men and women in agricultural workers. Married never-smoking women age 20-34 who currently work in Haikou Township, Anqing, who have obtained permission to have a child, and who will be attempting to become pregnant over the course of the study will be eligible for the study. Reproductive endpoints will include (1) semen parameters (concentration, total count, motility, progression and morphology), (2) menstrual disorders (oligomenorrhea, amenorrhea, polymenorrhea, intermenstrual bleeding, prolonged menstrual bleeding, dysmenorrhea, and irregular menstruation); (3) alterations in hormone patterns including reduced estrogen excretion (REE), anovulation, abnormal luteal phase (ALP), and abnormal follicular phase (AFP) in women and abnormalities of LH, FSH, TSH, SHBG, inhibin-B and testosterone in men; (4) fecundability; and (5) pregnancy outcomes including spontaneous abortion, preterm delivery, low birth weight and intrauterine growth retardation. After enrollment, interviewers will administer a previously validated questionnaire to the women and their husbands to collect baseline information on sociodemographic, environmental, occupational, and personal covariates. Semen samples will be obtained by trained technicians at enrollment and again four months later. Each woman will keep a diary of her menstrual information, environmental exposures, and dietary intake. Daily urine samples will be collected from each female subject for up to one year or until a pregnancy occurs. Urinary PdG, EIC, LH, FSH and hCG will be measured to identify abnormal endocrine patterns and subclinical pregnancy. Once a woman becomes pregnant, she will be followed for pregnancy outcomes obtained from a follow-up survey and hospital records where the baby is delivered. Extensive exposure assessment will be conducted throughout the follow-up period and, therefore, dose-response relationships can be established. All participants will keep daily exposure diaries. Urine samples will be measured for metabolites on selected exposure days. A subset of participants will be studied for personal air monitoring and serial analysis of urine metabolites to validate the exposure diary and urine metabolite assay. The investigators state that the proposed study has several strengths: (1) it will be conducted in a population with a broad range of organophosphate pesticide exposure; (2) exposure will be well-characterized; (3) each woman and her husband will be studied simultaneously; (4) the prospective study design can eliminate certain flaws or potential biases in previous retrospective studies; (5) time to conception and spontaneous abortion will be evaluated with the improved specific hCG assay, which can detect pregnancy within a few days of implantation; (6) recently-developed biomarkers, including urinary hormone assays and FISH methods, will be applied to the study; (7) gene-environment interactions will be tested; (8) the field cost in China is much lower than that in the U.S.; and (9) the population possesses unique characteristics for examining the proposed hypothesis, i.e., a stable workforce, a non-smoking group and excellent compliance rates.